Abstract

Abstract

The P-721 opaque (P-721Q) endosperm of sorghum [Sorghum bicolor (L.) Moenchl has better protein quality (lysine/protein ratio) than normal sorghum endosperms. However, sorghum with opaque endosperm has not been readily accepted for wide cultivation due to its lower yield potential and some other problems associated with its soft endosperm. The objective of this study was to determine whether hybrids between high yielding opaque lines resulted in heterotic response for grain yield and kernel weight without loss in protein quality. Each of 10 high lysine lines derived from P-721Q was mated with the same three cytoplasmic male-sterile lines, also derived from P-721Q by backcrossing to sterile cytoplasm. The F1 hybrids derived from these matings were field-evaluated for grain yield, 100-kernel weight, protein concentration, and lysine concentration in protein on a fine-silty, mixed, mesic Typic Haplaquoll. Significant differences among general combining ability effects were observed for all characters except grain yield, whereas significant differences among specific combining ability effects were observed for only grain yield. Correlation between grain yield and protein in the 30 hybrids was negative and significant (r = −0.63); correlation between grain yield and lysine concentration in protein was also negative but not significant. The best male parent, R-3 (P-850314), also produced hybrids with the highest lysine concentration. Among the female parents, A-3 (P-851063) gave hybrids with the highest protein quality. The best single-cross hybrid, A-3 ✕ R-3, for agronomic and protein quality, had 35% more lysine than the normal cultivar P-721N and yielded as much as the NK-180 check. Thus, this hybrid has the potential of substituting for other expensive protein and lyslne sources in the semiarid tropics.

Contribution from the Purdue Univ. Agric. Exp. Stn. Journal Paper no. 10 886. Part of a thesis submitted by the senior author in partial fulfillment of the M.S. degree.

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